1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/rust/proc-macro2/tests/marker.rs b/third_party/rust/proc-macro2/tests/marker.rs
new file mode 100644
index 0000000000..7af2539c1a
--- /dev/null
+++ b/third_party/rust/proc-macro2/tests/marker.rs
@@ -0,0 +1,59 @@
+use proc_macro2::*;
+
+macro_rules! assert_impl {
+    ($ty:ident is $($marker:ident) and +) => {
+        #[test]
+        #[allow(non_snake_case)]
+        fn $ty() {
+            fn assert_implemented<T: $($marker +)+>() {}
+            assert_implemented::<$ty>();
+        }
+    };
+
+    ($ty:ident is not $($marker:ident) or +) => {
+        #[test]
+        #[allow(non_snake_case)]
+        fn $ty() {
+            $(
+                {
+                    // Implemented for types that implement $marker.
+                    trait IsNotImplemented {
+                        fn assert_not_implemented() {}
+                    }
+                    impl<T: $marker> IsNotImplemented for T {}
+
+                    // Implemented for the type being tested.
+                    trait IsImplemented {
+                        fn assert_not_implemented() {}
+                    }
+                    impl IsImplemented for $ty {}
+
+                    // If $ty does not implement $marker, there is no ambiguity
+                    // in the following trait method call.
+                    <$ty>::assert_not_implemented();
+                }
+            )+
+        }
+    };
+}
+
+assert_impl!(Delimiter is Send and Sync);
+assert_impl!(Spacing is Send and Sync);
+
+assert_impl!(Group is not Send or Sync);
+assert_impl!(Ident is not Send or Sync);
+assert_impl!(LexError is not Send or Sync);
+assert_impl!(Literal is not Send or Sync);
+assert_impl!(Punct is not Send or Sync);
+assert_impl!(Span is not Send or Sync);
+assert_impl!(TokenStream is not Send or Sync);
+assert_impl!(TokenTree is not Send or Sync);
+
+#[cfg(procmacro2_semver_exempt)]
+mod semver_exempt {
+    use super::*;
+
+    assert_impl!(LineColumn is Send and Sync);
+
+    assert_impl!(SourceFile is not Send or Sync);
+}